We are, quite possibly, a nation increasingly afraid of the park – or, more precisely, the creatures that live there.

The U.S. Fish and Wildlife Service reported this week that many visitors to national wildlife refuges fear not only snakes, bats, alligators and wolves but even ducks and turtles. The agency shared anecdotal reports from refuge guides suggesting more and more visitors find creatures creepy.

In interviews, some of those guides say they aren't sure fear of wildlife is getting worse – but they do see a lot of it, in both children and adults who, they suspect, are more comfortable at home looking at screens than in a swamp looking at bats.

"It's a fear of the unknown," says Dave Sagan, a visitor services specialist at Great Swamp Refuge in New Jersey. A common fear among children visiting the swamp, a mere 26 miles from Manhattan, is that it's full of alligators, he says (it is not, though a refuge down in Florida has plenty).

People seem to expect the kind of killer creatures they see on TV nature shows, Sagan says. "Maybe there's a spider in Venezuela that will kill you if it bites you, but we don't have those kinds of creature around here."

The New Jersey refuge does have bats, and Sagan spends lots of time reassuring visitors that they aren't going to suck anyone's blood or land in their hair, though they do kill off a lot of pesky mosquitoes.

"A lot of folks today have very little experience outdoors," says Ashley Inslee, a biologist at Bosque del Apache Refuge in New Mexico. Inslee says she grew up enjoying the outdoors in rural Kansas, but many of the college students she takes on tours are from urban and suburban backgrounds.

They haven't done much hiking or camping, she says, and "they are lot more anxious about walking into a grove of trees" and possibly encountering a rattlesnake than more experienced folks might be.

Andrea Brophy, environmental education coordinator at the New Mexico refuge, works with younger children. She says it's their parents and teachers who get grossed out when she presents the kids with "owl pellets" – regurgitated wads of owl food – to dissect (she sterilizes them first).

Such squeamishness can rub off on kids, she says: "Adults set the tone."

That's important to remember, whether you are introducing your kids to the snakes at the nature preserve or the bugs in your backyard, says Bill Ulfelder, executive director of the New York chapter of the Nature Conservancy

Surveys by the group have found fear of bugs – and heat and rain – are among the reasons many kids say they don't like the outdoors. Those fears usually recede when parents routinely get kids out in all kinds of conditions (with the proper protective gear), he says.

Ulfelder says he sees a silver lining in the reports of frightened wildlife refuge visitors: "The good news is that these people are all out in wildlife refuges. … They've overcome the first barrier, which is getting outside at all."

Indeed, Sagan, the New Jersey guide, says one reason he and his colleagues may be seeing more nervous visitors is that they are seeing more visitors, period. Statistics from the wildlife service back him up: The nation's 562 refuges had 47 million visitors in 2013, up from 36.5 million in 2000.

The guides say they teach visitors to show wild animals the proper respect: to keep their distance from those rattlesnakes (they do bite), not to touch the bats (which can carry rabies) and never to feed the creatures. Still, Sagan says he tells them the scariest thing at the refuge is a "little old plant with leaves of three" — poison ivy.